On section Null-Valued Settings is not easy to understand that "show example.string" will result in an "ERROR: unrecognized...", that BEGIN or ROLLBACK does not return anything. So, what do you think about creating a table with two columns and showing command and result side by side ?
I think I'll replace the use of SHOW with current_setting throughout the entire example. That should increase the clarity and lets me return true/false with the column indicating the test - like the existing use of current_setting does.
David J.
p.s.
I really wish someone had gotten around to implementing \pset true 'true' and \pset false 'false' ... however we ended up with boolean outputs being "f" and "t" a bunch of people must have chosen to invest their life savings in eyewear companies.
